• BMB Reports
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• v.38 no.5
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• pp.624-631
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• 2005

Tuberculosis, caused by Mycobacterium tuberculosis, continues to be one of the main diseases to mankind. It is urgent to discover novel drug targets for appropriate antimicrobial agents against this human pathogen. The shikimate pathway is onsidered as an attractive target for the discovery of novel antibiotics for its essentiality in bacteria and absence in mammalian cells. The Mycobacterium tuberculosis aroE-encoded shikimate dehydrogenase was cloned, expressed and purified. Sequence alignment analysis shows that shikimate dehydrogenase of Mycobacterium tuberculosis exhibit the pattern of G-X-(N/S)-V-(T/S)-X-PX-K, which is highly conserved within the shikimate dehydrogenase family. The recombinant shikimate dehydrogenase spectrum determined by CD spectroscopy showed that the percentages for $\alpha$-helix, $\beta$-sheet, $\beta$-turn, and random coil were 29.2%, 9.3%, 32.7%, and 28.8%, respectively. The enzymatic characterization demonstrates that it appears to be fully active at pH from 9.0 to 12, and temperature $63^{\circ}C$. The apparent Michaelis constant for shikimic acid and $NADP^+$ were calculated to be about $29.5\;{\mu}M$ and $63\;{\mu}M$. The recombinant shikimate dehydrogenase catalyzes the substrate in the presence of $NADP^+$ with an enzyme turnover number of $399\;s^{-1}$. Zymological studies suggest that the cloned shikimate dehydrogenase from M. tuberculosis has a pretty activity, and the work should help in the discovery of enzyme inhibitors and further of possible antimicrobial agents against Mycobacterium tuberculosis.

• Journal of Microbiology and Biotechnology
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• v.31 no.9
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• pp.1305-1310
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• 2021

Shikimate is a key high-demand metabolite for synthesizing valuable antiviral drugs, such as the anti-influenza drug, oseltamivir (Tamiflu). Microbial-based strategies for shikimate production have been developed to overcome the unstable and expensive supply of shikimate derived from traditional plant extraction processes. In this study, a microbial cell factory using Corynebacterium glutamicum was designed to overproduce shikimate in a fed-batch culture system. First, the shikimate kinase gene (aroK) responsible for converting shikimate to the next step was disrupted to facilitate the accumulation of shikimate. Several genes encoding the shikimate bypass route, such as dehydroshikimate dehydratase (QsuB), pyruvate kinase (Pyk1), and quinate/shikimate dehydrogenase (QsuD), were disrupted sequentially. An artificial operon containing several shikimate pathway genes, including aroE, aroB, aroF, and aroG were overexpressed to maximize the glucose uptake and intermediate flux. The rationally designed shikimate-overproducing C. glutamicum strain grown in an optimized medium produced approximately 37.3 g/l of shikimate in 7-L fed-batch fermentation. Overall, rational cell factory design and culture process optimization for the microbial-based production of shikimate will play a key role in complementing traditional plant-derived shikimate production processes.

• Journal of Microbiology and Biotechnology
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• v.33 no.10
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• pp.1370-1375
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• 2023

In this study, we aimed to enhance the accumulation of chorismate (CHR) and anthranilate (ANT), key intermediates in the shikimate pathway, by modifying a shikimate over-producing recombinant strain of Corynebacterium glutamicum [19]. To achieve this, we utilized a CRISPR-driven genome engineering approach to compensate for the deletion of shikimate kinase (AroK) as well as ANT synthases (TrpEG) and ANT phosphoribosyltransferase (TrpD). In addition, we inhibited the CHR metabolic pathway to induce CHR accumulation. Further, to optimize the shikimate pathway, we overexpressed feedback inhibition-resistant Escherichia coli AroG and AroH genes, as well as C. glutamicum AroF and AroB genes. We also overexpressed QsuC and substituted shikimate dehydrogenase (AroE). In parallel, we optimized the carbon metabolism pathway by deleting the gntR family transcriptional regulator (IolR) and overexpressing polyphosphate/ATP-dependent glucokinase (PpgK) and glucose kinase (Glk). Moreover, acetate kinase (Ack) and phosphotransacetylase (Pta) were eliminated. Through our CRISPR-driven genome re-design approach, we successfully generated C. glutamicum cell factories capable of producing up to 0.48 g/l and 0.9 g/l of CHR and ANT in 1.3 ml miniature culture systems, respectively. These findings highlight the efficacy of our rational cell factory design strategy in C. glutamicum, which provides a robust platform technology for developing high-producing strains that synthesize valuable aromatic compounds, particularly those derived from the shikimate pathway metabolites.

• Journal of Microbiology and Biotechnology
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• v.32 no.8
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• pp.1011-1016
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• 2022

Bacillus subtilis is a useful bacterium in the food industry with applications as a starter strain for fermented food and as a probiotic. However, it is difficult to discriminate B. subtilis from other Bacillus species because of high phenotypic and genetic similarity. In this study, we employed five previously constructed multilocus sequence typing (MLST) methods for the discrimination of B. subtilis from other Bacillus species and all five MLST assays clearly distinguished B. subtilis. Additionally, the 17 housekeeping genes used in the five MLST assays also clearly distinguished B. subtilis. The pyruvate carboxylase (pyrA) and shikimate dehydrogenase (aroE) genes were selected for the discrimination of B. subtilis because of their high number of polymorphic sites and the fact that they displayed the lowest homology among the 17 housekeeping genes. Specific primer sets for the pyrA and aroE genes were designed and PCR products were specifically amplified from B. subtilis, demonstrating the high specificity of the two housekeeping genes for B. subtilis. This species-specific PCR method provides a quick, simple, powerful, and reliable alternative to conventional methods in the detection and identification of B. subtilis.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2005.11a
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• pp.106-111
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• 2005

For breeding of a new rootstock for eggplant production, somatic hybrids between two species, Solanum integrifolium and S. sanitwongsei were obtained through protoplast fusion. The former species has been commonly used for rootstock for eggplant production in Japan. Eggplants on these rootstocks are more productive than ungrafted plants, but are susceptible to bacterial wilt caused Ralstonia solanacearum. While the latter species is resistant, the growth of eggplants on this rootstock is rather slow and low yield. Protoplast of both species were isolated from cotyledons, and inactivated with iodoacetamide or UV-irradiation, then fused electrically. The fused products were then cultured. Regenerated plantlets were then transplanted on soil then maintained in a green house. The plants were classified into four groups. Those in the first group showed morphological characters intermediate of the parentalspecies. The plants bore fruit with viable seeds. The plants showed a chromosome number of 2n=48, the sum of those of the parental species, and are suggested to be symmetric fusion products. While plants in the other groupswas less vigorous and showed chromosome number 2n= 68 to 72 suggesting asymmetric fusion products by genomic in situ hybridization(GISH). Isozyme pattern of shikimate dehydrogenase (SKDH; EC 1.1.1.25), isocitrate dehydrogenase (IDH; EC 1.1.1.41) and phosphoglucomutase (PGM; EC 2.7.5.1) showed that 24 regenerated plants in three groups were somatic hybrids. Analysis of random amplified polymorphic DNA (RAPD) showed that 43 S. integrifolium-specific and 57 S. sanitwongsei-specific bands were all found in 24 plants. Both somatic hybrids and its S1 plants were found to be resistant to bacterial wilt, and eggplant grafted these plants using for rootstocks were more productive than grafted mother plants. Now, S1 progenies are used for commercial eggplant production in Osaka Prefecture.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1766-1772
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• 2009

In this study, we are interested in comparing the protein profiles of acid-shocked and control cells of S. mutans isolated from Korean children with caries. The results of 2D gel electrophoresis showed that twelve proteins are up-regulated when the cells were grown under 20 mM lactic acid stress in the exponential phase. Up-proteins under acid stress were estimated a major key of the survival and proliferation of S. mutans in low pH environments. These proteins are estimated generally associated with three biochemical pathways: glycolysis, alternative acid production and branched-chain amino acid biosynthesis.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.167-167
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• 2017

Our previous study for developing seeds of Iksan 526 (I.526), an inbred line of resveratrol-producing transgenic rice line, showed that, in 20 days after heading (DAH) seeds, resveratrol was almost saturated and accumulation of piceid was highest though the expression of Arachis hypogaea resveratrol synthase 3 (AhRS3, GenBank DQ124938) was highest in 31 DAH seeds. In this study, it was investigated how the overexpression of AhRS3 affects phenylpropanoid pathway genes. p-Coumaroyl-CoA is derived from phenylpropanoid pathway and used as a substrate of AhRS3 reaction for resveratrol production. In 6, 13, 20, 31 and 41 (45 for Dongjin) DAH seeds of I526 and Dongjin, a wild type of I.526, respectively, the expression pattern of phenylpropanoid pathway genes, including phenylalanine ammonia-lyase (PAL: LOC_Os02g41630.2, LOC_Os04g43760.1), cinnamate 4-hydroxylase (C4H: LOC_Os05g25640.1), 4-coumarate-CoA ligase (4CL: LOC_Os02g08100.1), cinnamoyl-CoA reductase (CCR: LOC_ Os09g25150.1, LOC_Os08g34280.1), hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyl transferase (HCT: LOC_Os04g42250.2, LOC_Os02g39850.1) and cinnamyl alcohol dehydrogenase (CAD: LOC_Os02g09490.1), was examined using real time (RT)-PCR. Compared to developing seeds of Dongjin, RT-PCR results showed that the expression pattern of phenylpropanoid pathway genes was modified in developing seeds of I.526. In most genes, except for CAD, of I.526 developing seeds, the gene expression was highest in 20 DAH corresponding to biosynthesis of resveratrol and piceid, i.e. the expression of phenylpropanoid pathway genes was gradually increased by 20 DAH and decreased as seeds develop. Especially, in Dongjin, the highest expression of PALs and 4CL was in 6 DAH and their expression was gradually decreased as seeds develop. These genes expression data also exhibited that, in developing seeds of I.526, phenylpropanoid pathway genes were slightly or significantly (in some genes) upregulated compared to Dongjin. Therefore, the overexpression of AhRS3 changed the expression pattern of phenylpropanoid pathway genes in I.526 developing seeds and this modification for gene expression is closely related to biosynthesis of resveratrol and piceid.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.105-105
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• 2017

Our previous study for developing seeds of Iksan 526 (I.526), an inbred line of resveratrol-producing transgenic rice line, showed that, in 20 days after heading (DAH) seeds, resveratrol was almost saturated and accumulation of piceid was highest though the expression of Arachis hypogaea resveratrol synthase 3 (AhRS3, GenBank DQ124938) was highest in 31 DAH seeds. In this study, it was investigated how the overexpression of AhRS3 affects phenylpropanoid pathway genes. p-Coumaroyl-CoA is derived from phenylpropanoid pathway and used as a substrate of AhRS3 reaction for resveratrol production. In 6, 13, 20, 31 and 41 (45 for Dongjin) DAH seeds of I526 and Dongjin, a wild type of I.526, respectively, the expression pattern of phenylpropanoid pathway genes, including phenylalanine ammonia-lyase (PAL: LOC_Os02g41630.2, LOC_Os04g43760.1), cinnamate 4-hydroxylase (C4H: LOC_Os05g25640.1), 4-coumarate-CoA ligase (4CL: LOC_Os02g08100.1), cinnamoyl-CoA reductase (CCR: LOC_Os09g25150.1, LOC_Os08g34280.1), hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyl transferase (HCT: LOC_Os04g42250.2, LOC_Os02g39850.1) and cinnamyl alcohol dehydrogenase (CAD: LOC_Os02g09490.1), was examined using real time (RT)-PCR. Compared to developing seeds of Dongjin, RT-PCR results showed that the expression pattern of phenylpropanoid pathway genes was modified in developing seeds of I.526. In most genes, except for CAD, of I.526 developing seeds, the gene expression was highest in 20 DAH corresponding to biosynthesis of resveratrol and piceid, i.e. the expression of phenylpropanoid pathway genes was gradually increased by 20 DAH and decreased as seeds develop. Especially, in Dongjin, the highest expression of PALs and 4CL was in 6 DAH and their expression was gradually decreased as seeds develop. These genes expression data also exhibited that, in developing seeds of I.526, phenylpropanoid pathway genes were slightly or significantly (in some genes) upregulated compared to Dongjin. Therefore, the overexpression of AhRS3 changed the expression pattern of phenylpropanoid pathway genes in I.526 developing seeds and this modification for gene expression is closely related to biosynthesis of resveratrol and piceid.